I'd suggest contacting your hosting provider for further assistance(*). They should be in the best position to assist you with recovering the site quickly and efficiently.

Once this is done, you'll need (unless you want a re-occurance) to find the hole and fix it. Updating as suggested 'may' be sufficient; but again, you hosting provider(*) should be able to assist in identification of the successful attack vector.

And judging from the defacement page message, I'd possibly also suggest not annoying the less trustworthy denizens of the 'net.

N.B. (*), depending on service contract, additional assistance in this matter may chargeable etc.